A flash device is usually used when an object or field to be photographed is relatively dark. Nonetheless, it is impossible to give a uniform or general standard of brightness or darkness at which a flash device is to be used for synchronized photographing. This decision is commonly left to an individual photographer's determination. It is for this reason that synchronized photographing illuminated with a flash device is often overexposed.
This problem has been substantially overcome by a flash device having an automatic light quantity adjusting function in which the time duration for flash light discharge depends upon various optical factors including the object distance and the luminance of the object. However, the problem still remains unresolved for compact flash devices having no such adjusting function, for example, a flash device incorporated into the camera body.
A similar problem is also encountered when a photographer is photographing a relatively bright object without resetting a flash device already set to be ready for flash discharge. Although the operation of the flash device is easily prevented by, for example, the opening of a source switch for the flash light, it is not uncommon for the photographer to forget to disable flash light discharge especially when an object to be photographed suddenly becomes bright during synchronized flash light photographing.
To overcome the above-mentioned problems the present invention provides an improved photographic flash device wherein the device is prevented from firing a flash light when an object to be photographed is brighter than a predetermined level but wherein flash light triggering is enabled when the object to be photographed is darker than the predetermined level.